Our long term objectives are to understand the mechanism of integration of the autonomic, somatic and neuroendocrine systems in the control of body functions. For this grant period we chose to concentrate on the study of autonomic-neuroendocrine integration in anesthetized animals (mainly cats and dogs). Our immediate objectives are described under four projects. 1) The functional role played by neurosecretory and non-neurosecretory neurons in and near the paraventricular (PVN) and supraoptic (SON) nuclei which project "directly" to the spinal cord on cardiovascular regulation will be determined, 2) The direct and indirect projections of the PVN and the SON neurons to sympathetic and parasympathetic neurons in the lumbar and the sacral spinal cord will be studied with electrophysiological techniques. Role of the PVN and the SON neurons in the control of the bladder, colon and the rectum through autonomic nerves will be determined. 3) Relationships between the PVN-SON neurons (both neurosecretory and non-neurosecretory) and ventrolateral medulla where noradrenergic neuron groups are located will be studied. The importance of these connections in the cardiovascular function will be assessed. 4) The two way connections between neurons in the subfornical organ and those in the PVN and the SON will be studied by using electrical and chemical stimulations of one group and recordings of antidromically and orthodromically evoked activity in the other group of neurons, and finally the role played by the subfornical organ in cardiovascular regulation and the involvement of the PVN in such role will also be investigated. Studies of responses of different types of neurons in the subfornical organ to excitation of baro- and chemoreceptors, changes in cardiovascular reflexes produced by stimulation (chemical and electrical) of the subfornical organ will provide useful information. Study of the mechanism of integration between autonomic nerves, the hypothalamic hormones (vasopressin and oxytocin) and metabolism will lead to a better understanding of control of blood pressure and hypertension in man.